There have been generally used soybean lecithin, sucrose fatty acid ester, glycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester as the food surfactant, conventionally. Among them, soybean lecithin has been modified for the objective specifically to improve the HLB value thereof. That is, although soybean lecithin is excellent in terms of safety, its HLB value is as low as 3 to 8, which results in the disadvantages not only that the lecithin is difficult to be dissolved in water but that its surfacting action is exhibited only within a limited range, involving the limited use thereof. For that reason, investigation has been carried out over the modification of soybean lecithin in order to provide it with an HLB value approximately at the same degree of that of other higher HLB emulsifiers.
Soybean lecithin has been modified by a variety of means including transphosphatidylation (Japanese Patent Laid-open No.61-199749), acetylation, hydroxylation, hydrolysis of fatty acid moiety, owing to the easy modifiable molecular structure thereof. Consequently, transfer lecithin is in practical use on confirmation that transfer lecithin in which the choline bonded with the phosphoryl group of lecithin is substituted with polyhydric alcohol such as glycerol, glucose, sorbitol and the like, has an HLB value of about 15.
However, some other surfactants produced by chemical synthesis, for example the sucrose fatty acid ester in which the monoester content is increased to 95% or more, have an HLB value of nearly 20, and they are popularly used in various fields due to the excellent and unique surfacting action owing to the high HLB thereof.